U.S. patent application number 13/336607 was filed with the patent office on 2013-06-27 for thermal imaging camera for infrared rephotography.
This patent application is currently assigned to Fluke Corporation. The applicant listed for this patent is Jody Forland, Kirk R. Johnson, Reed S. Nelson, Mark J. Patton, Jeffrey M. Wisted. Invention is credited to Jody Forland, Kirk R. Johnson, Reed S. Nelson, Mark J. Patton, Jeffrey M. Wisted.
Application Number | 20130162835 13/336607 |
Document ID | / |
Family ID | 47435779 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130162835 |
Kind Code |
A1 |
Forland; Jody ; et
al. |
June 27, 2013 |
THERMAL IMAGING CAMERA FOR INFRARED REPHOTOGRAPHY
Abstract
Thermal imaging cameras for use in retaking images and methods
of retaking images with thermal imaging cameras that include a
position sensor that helps guide the camera back to the position
where the original image was captured. The position sensor provides
position data that may include location data, heading data, and
orientation data.
Inventors: |
Forland; Jody; (St.
Bonifacius, MN) ; Johnson; Kirk R.; (Rogers, MN)
; Patton; Mark J.; (Maple Grove, MN) ; Wisted;
Jeffrey M.; (Burnsville, MN) ; Nelson; Reed S.;
(Shoreview, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Forland; Jody
Johnson; Kirk R.
Patton; Mark J.
Wisted; Jeffrey M.
Nelson; Reed S. |
St. Bonifacius
Rogers
Maple Grove
Burnsville
Shoreview |
MN
MN
MN
MN
MN |
US
US
US
US
US |
|
|
Assignee: |
Fluke Corporation
Everett
WA
|
Family ID: |
47435779 |
Appl. No.: |
13/336607 |
Filed: |
December 23, 2011 |
Current U.S.
Class: |
348/164 ;
348/E5.09 |
Current CPC
Class: |
H04N 5/332 20130101;
H04N 5/23222 20130101 |
Class at
Publication: |
348/164 ;
348/E05.09 |
International
Class: |
H04N 5/33 20060101
H04N005/33 |
Claims
1. A portable, hand-held thermal imaging camera comprising: an
infrared (IR) lens assembly having an associated IR sensor for
detecting thermal images of a target scene; a visible light (VL)
lens assembly having an associated VL sensor for detecting VL
images of the target scene; a display adapted to display at least a
portion of the VL image or at least a portion of the IR image; a
processor; a position sensor adapted to provide position data to
the processor, the position data representative of the position of
the camera; a memory adapted for storing a first infrared image of
a scene captured at a first position and first position data,
wherein the first infrared image and first position data may be
been captured by the thermal imaging camera or by a separate
thermal imaging camera; the processor programmed with instructions
to compare position data for a current position of the camera to
the first position data and generate a signal to a user how to
reposition the camera toward the first position.
2. The thermal imaging camera of claim 1, wherein the position
sensor comprises an accelerometer.
3. The thermal imaging camera of claim 2, wherein the position
sensor includes a compass and the position data includes heading
data.
4. The thermal imaging camera of claim 3, further comprising a
laser adapted to measure a distance-to-target and wherein the laser
is adapted to provide further position data to the processor.
5. The thermal imaging camera of claim 1, wherein the position data
comprises location data, heading data, and orientation data.
6. The thermal imaging camera of claim 1, wherein the position data
for the current position comprises data from the accelerometer,
compass, and laser.
7. The thermal imaging camera of claim 1, wherein the position
sensor comprises a GPS receiver.
8. The thermal imaging camera of claim 7, wherein the position data
comprises GPS coordinates.
9. The thermal imaging camera of claim 1, wherein the position
sensor continues to provide location data when the thermal imaging
camera is transported indoors.
10. The thermal imaging camera of claim 1, wherein the display is
adapted to display the signal generated by the processor.
11. The thermal imaging camera of claim 1, wherein the display
displays a sight to indicate to the user how to reposition the
camera toward the first position
12. The thermal imaging camera of claim 1, wherein the memory is
adapted to store settings data providing information regarding the
settings used on the thermal imaging camera when capturing the
first infrared image, and wherein the processor applies at least
some of the settings data to the thermal imaging camera when
capturing a second infrared image.
13. A method of retaking an infrared image of a scene using a
handheld, portable thermal imaging camera, comprising: retrieving a
first image and first image position data from the thermal imaging
camera, wherein the first image position data indicates a first
position of the thermal imaging camera when the first image was
captured; obtaining current position data, the current position
data indicating a current position of the thermal imaging camera;
comparing the first image position data and the current position
data; providing an indication, from the thermal imaging camera, how
to reposition the thermal imaging camera toward the first position;
and capturing a second image when the thermal imaging camera is
positioned at or near the first position, wherein the second image
comprises a thermal image or a fused thermal image and visible
light image.
14. The method of claim 13, wherein the first image position data
and the current image position data include data from an
accelerometer.
15. The method of claim 14, wherein the first image position data
and the current image position data further include data from a
compass.
16. The method of claim 15, wherein the first image position data
and the current image position data further include
distance-to-target data.
17. The method of claim 13, wherein the first image position data
and the current image position data include GPS coordinates.
18. The method of claim 13, wherein the first image and the second
image are captured by different thermal imaging cameras.
19. The method of claim 13, wherein the indication from the thermal
imaging camera how to reposition the thermal imaging camera toward
the first position is provided on a display of the thermal imaging
camera.
20. The method of claim 13, wherein the current position data and
the first position data comprise location data, heading data, and
orientation data.
21. The method of claim 13, wherein the current position data is
obtained when the thermal imaging camera is transported
indoors.
22. The method of claim 13, wherein the indication of how to
reposition the thermal imaging camera toward the first position is
provided via a display on the thermal imaging camera.
23. The method of claim 13, further comprising storing settings
data in the thermal imaging camera regarding the settings used on
the thermal imaging camera when capturing the first infrared image,
and applying the settings from the stored settings data to the
thermal imaging camera when capturing the second image.
Description
RELATED APPLICATIONS
[0001] The present application is related to the following commonly
assigned utility patent applications, which are hereby incorporated
by reference in their entireties: THERMAL IMAGING CAMERA FOR
INFRARED REPHOTOGRAPHY, Ser. No. 13/331,633, filed Dec. 20, 2011;
and THERMAL IMAGING CAMERA FOR INFRARED REPHOTOGRAPHY, Ser. No.
13/331,644, filed Dec. 20, 2011. Any portion of the methods or
portions of the cameras described in this related application for
retaking an infrared photograph may be combined with any of the
methods or cameras described herein for retaking an infrared
photograph. For instance, the method steps or the programming of
the processors for returning the camera to the position of the
first photograph described in the these related applications may be
combined with the method steps or the programming of the processor
for returning the camera to the position of the first photograph
described in the instant application.
TECHNICAL FIELD
[0002] This disclosure relates to thermal imaging cameras and, more
particularly, to thermal imaging cameras for use in retaking
infrared images.
BACKGROUND
[0003] Thermal imaging cameras are used in a variety of situations.
For example, thermal imaging cameras are often used during
maintenance inspections to thermally inspect equipment. Example
equipment may include rotating machinery, electrical panels, or
rows of circuit breakers, among other types of equipment. Thermal
inspections can detect equipment hot spots such as overheating
machinery or electrical components, helping to ensure timely repair
or replacement of the overheating equipment before a more
significant problem develops.
[0004] Depending on the configuration of the camera, the thermal
imaging camera may also generate a visible light image of the same
object. The camera may display the infrared image and the visible
light image in a coordinated manner, for example, to help an
operator interpret the thermal image generated by the thermal
imaging camera. Unlike visible light images which generally provide
good contrast between different objects, it is often difficult to
recognize and distinguish different features in a thermal image as
compared to the real-world scene. For this reason, an operator may
rely on a visible light image to help interpret and focus the
thermal image.
[0005] In applications where a thermal imaging camera is configured
to generate both a thermal image and a visual light image, the
camera may include two separate sets of optics: visible light
optics that focus visible light on a visible light sensor for
generating the visible light image, and infrared optics that focus
infrared radiation on an infrared sensor for generating the
infrared optics.
[0006] It is sometimes useful to compare infrared images from the
past to current infrared images of the same object or objects. In
this way, changes can be detected which might not otherwise be
apparent by observing only the current image. However, if the
positioning of the camera and the conditions under which the images
were captured in the past are not the same as those under which the
current image is captured, the infrared image of the object may
appear to have changed when no change has actually occurred, or it
may appear to have changed more or less than it actually has.
Therefore, in order for the comparison to be as accurate as
possible, the images which are being compared should be captured
from the same location and under the same conditions. However,
finding the precise camera location and determining that the exact
same conditions are applied can be very difficult and time
consuming. It would therefore be useful to improve the ease with
which thermal images can be repeated for purposes of detecting
changes over time.
SUMMARY
[0007] Certain embodiments of the invention include a thermal
imaging camera for use in retaking infrared images. In certain
embodiments, the camera is a hand-held, portable thermal imaging
camera that includes an infrared (IR) lens assembly with an
associated IR sensor for detecting thermal images of a target
scene. The camera also includes a visible light (VL) lens assembly
with an associated VL sensor for detecting VL images of the target
scene. The camera also includes a display, a processor, a position
sensor, and a memory. The display is adapted to display at least a
portion of the VL or IR images. The position sensor is adapted to
provide position data to the processor that is representative of
the position of the camera. The memory is adapted for storing a
first infrared image of a scene captured at a first position and
first position data. The first infrared image and the first
position data may be captured by the thermal imaging camera for by
a separate thermal imaging camera. The processor is programmed with
instructions to compare position data for a current position of the
camera to the first position data and generate a signal to a user
how to reposition the camera toward the first position.
[0008] Certain embodiments of the invention include a method of
retaking an infrared image of a scene using a handheld, portable
thermal imaging camera. The method includes retrieving a first
image and first image position data from the thermal imaging
camera, where the first image position data indicates a first
position of the thermal imaging camera when the first image was
captured. The method includes obtaining current position data that
indicates a current position of the thermal imaging camera. The
method also includes comparing the first image position data and
the current position data and providing an indication, from the
thermal imaging camera, how to reposition the thermal imaging
camera toward the first position. The method also includes
capturing a second image when the thermal imaging camera is
positioned at or near the first position. The second image may
include a thermal image or a fused thermal image and visible light
image.
[0009] The details of one or more examples are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a perspective front view of an example thermal
imaging camera.
[0011] FIG. 2 is a perspective back view of the example thermal
imaging camera of FIG. 1.
[0012] FIG. 3 is a functional block diagram illustrating example
components of the thermal imaging camera of FIGS. 1 and 2.
[0013] FIG. 4 is a conceptual illustration of an example
picture-in-picture type concurrent display of a visual image and an
infrared image.
[0014] FIG. 5 is a functional block diagram illustrating some of
the components of a position sensor according to certain
embodiments of the invention.
[0015] FIG. 6 is a flow chart of a process for positioning a
thermal imaging camera for retaking an image.
DETAILED DESCRIPTION
[0016] The following detailed description is exemplary in nature
and is not intended to limit the scope, applicability, or
configuration of the invention in any way. Rather, the following
description provides some practical illustrations for implementing
examples of the present invention. Examples of constructions,
materials, dimensions, and manufacturing processes are provided for
selected elements, and all other elements employ that which is
known to those of ordinary skill in the field of the invention.
Those skilled in the art will recognize that many of the noted
examples have a variety of suitable alternatives.
[0017] A thermal imaging camera may be used to detect heat patterns
across a scene under observation. The thermal imaging camera may
detect infrared radiation given off by the scene and convert the
infrared radiation into an infrared image indicative of the heat
patterns. In some examples, the thermal imaging camera may also
capture visible light from the scene and convert the visible light
into a visible light image. Depending on the configuration of the
thermal imaging camera, the camera may include infrared optics to
focus the infrared radiation on an infrared sensor and visible
light optics to focus the visible light on a visible light sensor.
In order to detect changes in the infrared radiation over time,
embodiments of the invention enable a user to retake an infrared
image or fused infrared and visible light image in the same
position or nearly the same position as an earlier infrared image
or fused infrared and visible light image. In this way, the earlier
infrared image or fused infrared and visible light images may be
compared to the present infrared image or fused infrared and
visible light image, so that changes in the infrared aspect of the
image, representing changes in heat patterns, may be more easily
identified. Furthermore, in order to make the comparison as
accurate as possible, embodiments of the invention may direct a
user to move the thermal imaging camera to the same camera
positions as used when the earlier images were captured. For
example, the data providing the position of a thermal imaging
camera when a first infrared or fused image was captured may be
stored in association with the first image. Then, at a later time,
the camera may then use the position data, along with data
providing the current camera position, to direct the user to return
the thermal imaging camera to the same position.
[0018] In some embodiments, the data providing the position of the
thermal imaging camera may include the distance-to-target, the
specific point in an image at which the distance sensor is aimed
(the aiming point), and the orientation of the camera in space,
including pitch, roll, and yaw. By recreating each of these, the
original position of the thermal imaging camera can be repeated. In
other embodiments, the data regarding positioning can include
global position system (GPS) coordinates.
[0019] The detection of changes in the infrared image are
particularly useful in certain situations. For example, when an
object typically produces heat, it may be difficult to determine
whether or not the infrared image indicates a problem. However, a
comparison between an earlier and a later image may reveal that the
object is producing increased amounts of heat and, therefore, that
a problem may be present. For example, one could periodically
capture infrared images from approximately the same vantage point
of many different machines, including an industrial kiln or
industrial furnace. Such kilns contain refractory material and such
furnaces contain insulation. By monitoring the thermogram of such
devices over time and considering the rate of change of the
measured temperatures, a user can determine if or when the
refractory material or the insulation is deteriorating and may need
replacement. However, if the comparison reveals that heat
production is stable, then the object may be operating
normally.
[0020] FIGS. 1 and 2 show front and back perspective views,
respectively of an example thermal imaging camera 10, which
includes a housing 12, an infrared lens assembly 14, a visible
light lens assembly 16, a display 18, a laser 19, and a trigger
control 20. Housing 12 houses the various components of thermal
imaging camera 10. The bottom portion of thermal imager 10 includes
a carrying handle for holding and operating the camera via one
hand. Infrared lens assembly 14 receives infrared radiation from a
scene and focuses the radiation on an infrared sensor for
generating an infrared image of a scene. Visible light lens
assembly 16 receives visible light from a scene and focuses the
visible light on a visible light sensor for generating a visible
light image of the same scene. Thermal imaging camera 10 captures
the visible light image and/or the infrared image in response to
depressing trigger control 20. In addition, thermal imaging camera
10 controls display 18 to display the infrared image and the
visible light image generated by the camera, e.g., to help an
operator thermally inspect a scene. Thermal imaging camera 10 may
also include a focus mechanism coupled to infrared lens assembly 14
that is configured to move at least one lens of the infrared lens
assembly so as to adjust the focus of an infrared image generated
by the thermal imaging camera.
[0021] In operation, thermal imaging camera 10 detects heat
patterns in a scene by receiving energy emitted in the
infrared-wavelength spectrum from the scene and processing the
infrared energy to generate a thermal image. Thermal imaging camera
10 may also generate a visible light image of the same scene by
receiving energy in the visible light-wavelength spectrum and
processing the visible light energy to generate a visible light
image. As described in greater detail below, thermal imaging camera
10 may include an infrared camera module that is configured to
capture an infrared image of the scene and a visible light camera
module that is configured to capture a visible light image of the
same scene. The infrared camera module may receive infrared
radiation projected through infrared lens assembly 14 and generate
therefrom infrared image data. The visible light camera module may
receive light projected through visible light lens assembly 16 and
generate therefrom visible light data.
[0022] In some examples, thermal imaging camera 10 collects or
captures the infrared energy and visible light energy substantially
simultaneously (e.g., at the same time) so that the visible light
image and the infrared image generated by the camera are of the
same scene at substantially the same time. In these examples, the
infrared image generated by thermal imaging camera 10 is indicative
of localized temperatures within the scene at a particular period
of time while the visible light image generated by the camera is
indicative of the same scene at the same period of time. In other
examples, thermal imaging camera may capture infrared energy and
visible light energy from a scene at different periods of time.
[0023] The scene which is captured by the thermal imaging camera 10
depends upon its position and settings. The position includes not
only the location of the thermal imaging camera 10 within the 3
dimensions of space, but also the rotation of the thermal imaging
camera 10 within the 3 axis of rotation, for a total of at least 6
variables determining the camera's position. The camera settings
can include zoom, lens type or use of a supplemental lens, focal
distance, F-number, emissivity, reflected temperature settings,
transmission settings of a window, for example, and also affect the
image. Both the position and the settings are preferably reproduced
when an infrared image is recaptured or rephotographed for purposes
of determining the presence of change in the infrared image over
time. Embodiments of the invention may include storing information
relating to the position and settings used when capturing an
earlier thermal image or fused visible light and thermal image, and
this information may be used to reproduce the thermal imaging
camera position and settings at a later time.
[0024] Visible light lens assembly 16 includes at least one lens
that focuses visible light energy on a visible light sensor for
generating a visible light image. Visible light lens assembly 16
defines a visible light optical axis which passes through the
center of curvature of the at least one lens of the assembly.
Visible light energy projects through a front of the lens and
focuses on an opposite side of the lens. Visible light lens
assembly 16 can include a single lens or a plurality of lenses
(e.g., two, three, or more lenses) arranged in series. In addition,
visible light lens assembly 16 can have a fixed focus or can
include a focus adjustment mechanism for changing the focus of the
visible light optics. In examples in which visible light lens
assembly 16 includes a focus adjustment mechanism, the focus
adjustment mechanism may be a manual adjustment mechanism or an
automatic adjustment mechanism.
[0025] Infrared lens assembly 14 also includes at least one lens
that focuses infrared energy on an infrared sensor for generating a
thermal image. Infrared lens assembly 14 defines an infrared
optical axis which passes through the center of curvature of lens
of the assembly. During operation, infrared energy is directed
through the front of the lens and focused on an opposite side of
the lens. Infrared lens assembly 14 can include a single lens or a
plurality of lenses (e.g., two, three, or more lenses), which may
be arranged in series.
[0026] As briefly described above, thermal imaging camera 10
includes a focus mechanism for adjusting the focus of an infrared
image captured by the camera. In the example shown in FIGS. 1 and
2, thermal imaging camera 10 includes focus ring 24. Focus ring 24
is operatively coupled (e.g., mechanically and/or electrically
coupled) to at least one lens of infrared lens assembly 14 and
configured to move the at least one lens to various focus positions
so as to focus the infrared image captured by thermal imaging
camera 10. Focus ring 24 may be manually rotated about at least a
portion of housing 12 so as to move the at least one lens to which
the focus ring is operatively coupled. In some examples, focus ring
24 is also operatively coupled to display 18 such that rotation of
focus ring 24 causes at least a portion of a visible light image
and at least a portion of an infrared image concurrently displayed
on display 18 to move relative to one another. In different
examples, thermal imaging camera 10 may include a manual focus
adjustment mechanism that is implemented in a configuration other
than focus ring 24.
[0027] In some examples, thermal imaging camera 10 may include an
automatically adjusting focus mechanism in addition to or in lieu
of a manually adjusting focus mechanism. An automatically adjusting
focus mechanism may be operatively coupled to at least one lens of
infrared lens assembly 14 and configured to automatically move the
at least one lens to various focus positions, e.g., in response to
instructions from thermal imaging camera 10. In one application of
such an example, thermal imaging camera 10 may use laser 19 to
electronically measure a distance between an object in a target
scene and the camera, referred to as the distance-to-target.
Thermal imaging camera 10 may then control the automatically
adjusting focus mechanism to move the at least one lens of infrared
lens assembly 14 to a focus position that corresponds to the
distance-to-target data determined by thermal imaging camera 10.
The focus position may correspond to the distance-to-target data in
that the focus position may be configured to place the object in
the target scene at the determined distance in focus. In some
examples, the focus position set by the automatically adjusting
focus mechanism may be manually overridden by an operator, e.g., by
rotating focus ring 24.
[0028] Data of the distance-to-target, as measured by the laser 19,
can be stored and associated with the corresponding captured image.
For images which are captured using automatic focus, this data will
be gathered as part of the focusing process. In some embodiments,
the thermal imaging camera will also detect and save the
distance-to-target data when an image is captured. This data may be
obtained by the thermal imaging camera when the image is captured
by using the laser 19 or, alternatively, by detecting the lens
position and correlating the lens position to a known
distance-to-target associated with that lens position. The
distance-to-target data may be used by the thermal imaging camera
10 to direct the user to position the camera at the same distance
from the target, such as by directing a user to move closer or
further from the target based on laser measurements taken as the
user repositions the camera, until the same distance-to-target is
achieved as in an earlier image. The thermal imaging camera may
further automatically set the lenses to the same positions as used
in the earlier image, or may direct the user to reposition the
lenses until the original lens settings are obtained.
[0029] During operation of thermal imaging camera 10, an operator
may wish to view a thermal image of a scene and/or a visible light
image of the same scene generated by the camera. For this reason,
thermal imaging camera 10 may include a display. In the examples of
FIGS. 1 and 2, thermal imaging camera 10 includes display 18, which
is located on the back of housing 12 opposite infrared lens
assembly 14 and visible light lens assembly 16. Display 18 may be
configured to display a visible light image, an infrared image,
and/or a fused image that is a simultaneous display of the visible
light image and the infrared image. In different examples, display
18 may be remote (e.g., separate) from infrared lens assembly 14
and visible light lens assembly 16 of thermal imaging camera 10, or
display 18 may be in a different spatial arrangement relative to
infrared lens assembly 14 and/or visible light lens assembly 16.
Therefore, although display 18 is shown behind infrared lens
assembly 14 and visible light lens assembly 16 in FIG. 2, other
locations for display 18 are possible. Signals to the user
regarding repositioning of the thermal imaging camera 10 may also
be provided on the display 18, such as in the form of direction
arrows or words of instruction.
[0030] Thermal imaging camera 10 can include a variety of user
input media for controlling the operation of the camera and
adjusting different settings of the camera. Example control
functions may include adjusting the focus of the infrared and/or
visible light optics, opening/closing a shutter, capturing an
infrared and/or visible light image, or the like. In the example of
FIGS. 1 and 2, thermal imaging camera 10 includes a depressible
trigger control 20 for capturing an infrared and visible light
image, and buttons 28 for controlling other aspects of the
operation of the camera. A different number or arrangement of user
input media are possible, and it should be appreciated that the
disclosure is not limited in this respect. For example, thermal
imaging camera 10 may include a touch screen display 18 which
receives user input by depressing different portions of the
screen.
[0031] FIG. 3 is a functional block diagram illustrating components
of an example of thermal imaging camera 10, which includes an
infrared camera module 100, a visible light camera module 102, a
display 104, a processor 106, a user interface 108, a memory 110,
and a power supply 112, and a position sensor 118. Processor is
communicatively coupled to infrared camera module 100, visible
light camera module 102, display 104, user interface 108, position
sensor 118, and memory 110. Power supply 112 delivers operating
power to the various components of thermal imaging camera 10 and,
in some examples, may include a rechargeable or non-rechargeable
battery and a power generation circuit.
[0032] Infrared camera module 100 may be configured to receive
infrared energy emitted by a target scene and to focus the infrared
energy on an infrared sensor for generation of infrared energy
data, e.g., that can be displayed in the form of an infrared image
on display 104 and/or stored in memory 110. Infrared camera module
100 can include any suitable components for performing the
functions attributed to the module herein. In the example of FIG.
3, infrared camera module is illustrated as including infrared lens
assembly 14 and infrared sensor 114. As described above with
respect to FIGS. 1 and 2, infrared lens assembly 14 includes at
least one lens that takes infrared energy emitted by a target scene
and focuses the infrared energy on infrared sensor 114. Infrared
sensor 114 responds to the focused infrared energy by generating an
electrical signal that can be converted and displayed as an
infrared image on display 104.
[0033] Infrared lens assembly 14 can have a variety of different
configurations. In some examples, infrared lens assembly 14 defines
a F-number (which may also be referred to as a focal ratio or
F-stop) of a specific magnitude. A F-number may be determined by
dividing the focal length of a lens (e.g., an outermost lens of
infrared lens assembly 14) by a diameter of an entrance to the
lens, which may be indicative of the amount of infrared radiation
entering the lens. In general, increasing the F-number of infrared
lens assembly 14 may increase the depth-of-field, or distance
between nearest and farthest objects in a target scene that are in
acceptable focus, of the lens assembly. An increased depth of field
may help achieve acceptable focus when viewing different objects in
a target scene with the infrared optics of thermal imaging camera
10 set at a hyperfocal position. If the F-number of infrared lens
assembly 14 is increased too much, however, the spatial resolution
(e.g., clarity) may decrease such that a target scene is not in
acceptable focus.
[0034] Infrared sensor 114 may include one or more focal plane
arrays (FPA) that generate electrical signals in response to
infrared energy received through infrared lens assembly 14. Each
FPA can include a plurality of infrared sensor elements including,
e.g., bolometers, photon detectors, or other suitable infrared
sensor elements. In operation, each sensor element, which may each
be referred to as a sensor pixel, may change an electrical
characteristic (e.g., voltage or resistance) in response to
absorbing infrared energy received from a target scene. In turn,
the change in electrical characteristic can provide an electrical
signal that can be received by processor 106 and processed into an
infrared image displayed on display 104.
[0035] For instance, in examples in which infrared sensor 114
includes a plurality of bolometers, each bolometer may absorb
infrared energy focused through infrared lens assembly 14 and
increase in temperature in response to the absorbed energy. The
electrical resistance of each bolometer may change as the
temperature of the bolometer changes. Processor 106 may measure the
change in resistance of each bolometer by applying a current (or
voltage) to each bolometer and measure the resulting voltage (or
current) across the bolometer. Based on these data, processor 106
can determine the amount of infrared energy emitted by different
portions of a target scene and control display 104 to display a
thermal image of the target scene.
[0036] Independent of the specific type of infrared sensor elements
included in the FPA of infrared sensor 114, the FPA array can
define any suitable size and shape. In some examples, infrared
sensor 114 includes a plurality of infrared sensor elements
arranged in a grid pattern such as, e.g., an array of sensor
elements arranged in vertical columns and horizontal rows. In
various examples, infrared sensor 114 may include an array of
vertical columns by horizontal rows of, e.g., 16.times.16,
50.times.50, 160.times.120, 120.times.160, or 640.times.480. In
other examples, infrared sensor 114 may include a smaller number of
vertical columns and horizontal rows (e.g., 1.times.1), a larger
number vertical columns and horizontal rows (e.g.,
1000.times.1000), or a different ratio of columns to rows.
[0037] During operation of thermal imaging camera 10, processor 106
can control infrared camera module 100 to generate infrared image
data for creating an infrared image. Processor 106 can generate a
"frame" of infrared image data by measuring an electrical signal
from each infrared sensor element included in the FPA of infrared
sensor 114. The magnitude of the electrical signal (e.g., voltage,
current) from each infrared sensor element may correspond to the
amount of infrared radiation received by each infrared sensor
element, where sensor elements receiving different amounts of
infrared radiation exhibit electrical signal with different
magnitudes. By generating a frame of infrared image data, processor
106 captures an infrared image of a target scene at a given point
in time.
[0038] Processor 106 can capture a single infrared image or "snap
shot" of a target scene by measuring the electrical signal of each
infrared sensor element included in the FPA of infrared sensor 114
a single time. Alternatively, processor 106 can capture a plurality
of infrared images of a target scene by repeatedly measuring the
electrical signal of each infrared sensor element included in the
FPA of infrared sensor 114. In examples in which processor 106
repeatedly measures the electrical signal of each infrared sensor
element included in the FPA of infrared sensor 114, processor 106
may generate a dynamic thermal image (e.g., a video representation)
of a target scene. For example, processor 106 may measure the
electrical signal of each infrared sensor element included in the
FPA at a rate sufficient to generate a video representation of
thermal image data such as, e.g., 30 Hz or 60 Hz. Processor 106 may
perform other operations in capturing an infrared image such as
sequentially actuating a shutter (not illustrated) to open and
close an aperture of infrared lens assembly 14, or the like.
[0039] With each sensor element of infrared sensor 114 functioning
as a sensor pixel, processor 106 can generate a two-dimensional
image or picture representation of the infrared radiation from a
target scene by translating changes in an electrical characteristic
(e.g., resistance) of each sensor element into a time-multiplexed
electrical signal that can be processed, e.g., for visualization on
display 104 and/or storage in memory 110. Processor 106 may perform
computations to convert raw infrared image data into scene
temperatures including, in some examples, colors corresponding to
the scene temperatures.
[0040] Processor 106 may control display 104 to display at least a
portion of an infrared image of a captured target scene. In some
examples, processor 106 controls display 104 so that the electrical
response of each sensor element of infrared sensor 114 is
associated with a single pixel on display 104. In other examples,
processor 106 may increase or decrease the resolution of an
infrared image so that there are more or fewer pixels displayed on
display 104 than there are sensor elements in infrared sensor 114.
Processor 106 may control display 104 to display an entire infrared
image (e.g., all portions of a target scene captured by thermal
imaging camera 10) or less than an entire infrared image (e.g., a
lesser port of the entire target scene captured by thermal imaging
camera 10). Processor 106 may perform other image processing
functions, as described in greater detail below.
[0041] Although not illustrated on FIG. 3, thermal imaging camera
10 may include various signal processing or conditioning circuitry
to convert output signals from infrared sensor 114 into a thermal
image on display 104. Example circuitry may include a bias
generator for measuring a bias voltage across each sensor element
of infrared sensor 114, analog-to-digital converters, signal
amplifiers, or the like. Independent of the specific circuitry,
thermal imaging camera 10 may be configured to manipulate data
representative of a target scene so as to provide an output that
can be displayed, stored, transmitted, or otherwise utilized by a
user.
[0042] Thermal imaging camera 10 includes visible light camera
module 102. Visible light camera module 102 may be configured to
receive visible light energy from a target scene and to focus the
visible light energy on a visible light sensor for generation of
visible light energy data, e.g., that can be displayed in the form
of a visible light image on display 104 and/or stored in memory
110. Visible light camera module 102 can include any suitable
components for performing the functions attributed to the module
herein. In the example of FIG. 3, visible light camera module 102
is illustrated as including visible light lens assembly 16 and
visible light sensor 116. As described above with respect to FIGS.
1 and 2, visible light lens assembly 16 includes at least one lens
that takes visible light energy emitted by a target scene and
focuses the visible light energy on visible light sensor 116.
Visible light sensor 116 responds to the focused energy by
generating an electrical signal that can be converted and displayed
as a visible light image on display 104.
[0043] Visible light sensor 116 may include a plurality of visible
light sensor elements such as, e.g., CMOS detectors, CCD detectors,
PIN diodes, avalanche photo diodes, or the like. The number of
visible light sensor elements may be the same as or different than
the number of infrared light sensor elements.
[0044] In operation, optical energy received from a target scene
may pass through visible light lens assembly 16 and be focused on
visible light sensor 116. When the optical energy impinges upon the
visible light sensor elements of visible light sensor 116, photons
within the photodetectors may be released and converted into a
detection current. Processor 106 can process this detection current
to form a visible light image of the target scene.
[0045] During use of thermal imaging camera 10, processor 106 can
control visible light camera module 102 to generate visible light
data from a captured target scene for creating a visible light
image. The visible light data may include luminosity data
indicative of the color(s) associated with different portions of
the captured target scene and/or the magnitude of light associated
with different portions of the captured target scene. Processor 106
can generate a "frame" of visible light image data by measuring the
response of each visible light sensor element of thermal imaging
camera 10 a single time. By generating a frame of visible light
data, processor 106 captures visible light image of a target scene
at a given point in time. Processor 106 may also repeatedly measure
the response of each visible light sensor element of thermal
imaging camera 10 so as to generate a dynamic thermal image (e.g.,
a video representation) of a target scene, as described above with
respect to infrared camera module 100.
[0046] With each sensor element of visible light camera module 102
functioning as a sensor pixel, processor 106 can generate a
two-dimensional image or picture representation of the visible
light from a target scene by translating an electrical response of
each sensor element into a time-multiplexed electrical signal that
can be processed, e.g., for visualization on display 104 and/or
storage in memory 110.
[0047] Processor 106 may control display 104 to display at least a
portion of a visible light image of a captured target scene. In
some examples, processor 106 controls display 104 so that the
electrical response of each sensor element of visible light camera
module 102 is associated with a single pixel on display 104. In
other examples, processor 106 may increase or decrease the
resolution of a visible light image so that there are more or fewer
pixels displayed on display 104 than there are sensor elements in
visible light camera module 102. Processor 106 may control display
104 to display an entire visible light image (e.g., all portions of
a target scene captured by thermal imaging camera 10) or less than
an entire visible light image (e.g., a lesser port of the entire
target scene captured by thermal imaging camera 10).
[0048] As noted above, processor 106 may be configured to determine
a distance between thermal imaging camera 10 and an object in a
target scene captured by a visible light image and/or infrared
image generated by the camera. Processor 106 may determine the
distance based on a focus position of the infrared optics
associated with the camera. For example, processor 106 may detect a
position (e.g., a physical position) of a focus mechanism
associated with the infrared optics of the camera (e.g., a focus
position associated with the infrared optics) and determine a
distance-to-target value associated with the position. Processor
106 may then reference data stored in memory 110 that associates
different positions with different distance-to-target values to
determine a specific distance between thermal imaging camera 10 and
the object in the target scene.
[0049] In these and other examples, processor 106 may control
display 104 to concurrently display at least a portion of the
visible light image captured by thermal imaging camera 10 and at
least a portion of the infrared image captured by thermal imaging
camera 10. Such a concurrent display may be useful in that an
operator may reference the features displayed in the visible light
image to help understand the features concurrently displayed in the
infrared image, as the operator may more easily recognize and
distinguish different real-world features in the visible light
image than the infrared image. In various examples, processor 106
may control display 104 to display the visible light image and the
infrared image in side-by-side arrangement, in a picture-in-picture
arrangement, where one of the images surrounds the other of the
images, or any other suitable arrangement where the visible light
and the infrared image are concurrently displayed.
[0050] For example, processor 106 may control display 104 to
display the visible light image and the infrared image in a fused
arrangement. In a fused arrangement, the visible light image and
the infrared image may be superimposed on top of one another. An
operator may interact with user interface 108 to control the
transparency or opaqueness of one or both of the images displayed
on display 104. For example, the operator may interact with user
interface 108 to adjust the infrared image between being completely
transparent and completely opaque and also adjust the visible light
image between being completely transparent and completely opaque.
Such an example fused arrangement, which may be referred to as an
alpha-blended arrangement, may allow an operator to adjust display
104 to display an infrared-only image, a visible light-only image,
of any overlapping combination of the two images between the
extremes of an infrared-only image and a visible light-only
image.
[0051] Components described as processors within thermal imaging
camera 10, including processor 106, may be implemented as one or
more processors, such as one or more microprocessors, digital
signal processors (DSPs), application specific integrated circuits
(ASICs), field programmable gate arrays (FPGAs), programmable logic
circuitry, or the like, either alone or in any suitable
combination.
[0052] In general, memory 110 stores program instructions and
related data that, when executed by processor 106, cause thermal
imaging camera 10 and processor 106 to perform the functions
attributed to them in this disclosure. Memory 110 may include any
fixed or removable magnetic, optical, or electrical media, such as
RAM, ROM, CD-ROM, hard or floppy magnetic disks, EEPROM, or the
like. Memory 110 may also include a removable memory portion that
may be used to provide memory updates or increases in memory
capacities. A removable memory may also allow image data to be
easily transferred to another computing device, or to be removed
before thermal imaging camera 10 is used in another
application.
[0053] An operator may interact with thermal imaging camera 10 via
user interface 108, which may include buttons, keys, or another
mechanism for receiving input from a user. The operator may receive
output from thermal imaging camera 10 via display 104. Display 104
may be configured to display an infrared-image and/or a visible
light image in any acceptable palette, or color scheme, and the
palette may vary, e.g., in response to user control. In some
examples, display 104 is configured to display an infrared image in
a monochromatic palette such as grayscale or amber. In other
examples, display 104 is configured to display an infrared image in
a color palette such as, e.g., ironbow, blue-red, or other high
contrast color scheme. Combination of grayscale and color palette
displays are also contemplated.
[0054] While processor 106 can control display 104 to concurrently
display at least a portion of an infrared image and at least a
portion of a visible light image in any suitable arrangement, a
picture-in-picture arrangement may help an operator to easily focus
and/or interpret a thermal image by displaying a corresponding
visible image of the same scene in adjacent alignment. FIG. 4 is a
conceptual illustration of one example picture-in-picture type
display of a visual image 240 and an infrared image 242. In the
example of FIG. 4, visual image 240 surrounds infrared image 242,
although in other examples infrared image 242 may surround visual
image 240, or visual image 240 and infrared image 242 may have
different relative sizes or shapes than illustrated and it should
be appreciated that the disclosure is not limited in this
respect.
[0055] FIG. 4 is a functional block diagram illustrating some of
the components of the position sensor 118 according to certain
embodiments of the invention. In some embodiments, the position
sensor 118 includes an electronic compass located within the imager
housing that is configured to generate orientation information
(e.g., heading information) corresponding to the direction in which
the camera is pointed. The electronic compass may include a
magnetic sensor that is configured to generate magnetic field
signals that vary depending on the orientation of the camera in
three-dimensional space. For example, the electronic compass may
include a three-axis magnetic sensor that is configured to generate
magnetic field signals corresponding to three orthogonal components
(e.g., X, Y, and Z components) of a magnetic field.
[0056] Magnetic sensor is configured to measure the strength of a
magnetic field in the vicinity of the sensor. Magnetic sensor may
include multiple axes, where each axis of the magnetic sensor is
configured to measure a different orthogonal component of the
magnetic field in the vicinity of the sensor. For example, magnetic
sensor may be a three-axis magnetic sensor (e.g., a three-axis
magnetometer) that is configured to measure three orthogonal
components (e.g., X-, Y-, and Z-components) of a magnetic field in
the vicinity of the magnetic sensor. The magnetic field in the
vicinity of the sensor may be a combination of the earth's magnetic
field and spurious magnetic fields, e.g., generated by hard-iron
magnetic field interferences and/or soft-iron magnetic field
interferences.
[0057] During use, processor 106 can receive an electrical signal
from magnetic sensor of position sensor 118 representative of the
magnetic field strength measured by the magnetic sensor at any give
time. For example, in instances in which magnetic sensor is a
three-axis magnetic sensor, processor 106 may receive three
different electrical signals from magnetic sensor, where each
electrical signal corresponds to the strength of a different
orthogonal component of the magnetic field in the vicinity of the
sensor. Processor 106 may receive a first measurement associated
with a first axis of the three-axis magnetic sensor, a second
measurement associated with a second axis of the three-axis
magnetic sensor, and a third measurement associated with a third
axis of the three-axis magnetic sensor. The three measurements may
be captured or generated at substantially the same time (e.g., when
thermal imaging camera is in a given physical orientation), or the
three measurements may be captured or generated at different times.
In either example, the magnitude of the electrical signals received
from magnetic sensor of position sensor 118 may vary as the
physical orientation of thermal imaging camera 10 in changed in
three-dimensional space. The magnetic sensor can therefore supply
position data that includes heading data that indicates the
direction in which the camera 10 is pointed.
[0058] In some embodiments, the position sensor 118 may also
include an accelerometer that generates acceleration signals that
vary depending on the orientation of the camera in
three-dimensional space. For example, the position sensor 118 may
include a three-axis accelerometer that is configured to generate
acceleration signals corresponding to three orthogonal directions
(e.g., X, Y, and Z components) in a physical space. For instance,
the position sensor 118 may include a tilt compensated electronic
compass sensor module that combines a magnetic sensor and an
accelerometer. Thermal imaging camera may process magnetic field
strength signals and accelerometer signals generated by the compass
and the accelerometer of the position sensor 118 to determine an
orientation of the thermal imaging camera, e.g., relative to an
absolute reference system (e.g., X, Y, Z coordinate system) fixed
with respect to ground and an orientation of housing of the camera.
Thermal imaging camera may then store the orientation information
in memory and/or display the orientation information on
display.
[0059] To define the orientation coordinates of thermal imaging
camera 10 in three-dimensional space, three attitude angles may be
defined relative to a horizontal plane which is perpendicular to
the earth's gravitational force. In the example of FIG. 1, a
heading angle 23, a pitch angle 25, and a roll angle 27 are defined
with reference to a local horizontal plane which is perpendicular
to the earth's gravity. Heading angle 23, which may also be
referred to as an azimuth, is an angle that varies with respect to
the magnetic north pole. When rotating thermal imaging camera 10
around the Z-axis, the heading of the camera can be determined
relative to magnetic north. Pitch angle 25 is an angle between the
X-axis illustrated on FIG. 1 and the horizontal plane. Pitch angle
25 may vary between zero degrees and positive/minus ninety degrees
when rotating thermal imaging camera 10 around the Y-axis
illustrated on FIG. 1 with the X-axis moving upward. When rotating
thermal imaging camera 10 around the Y-axis illustrated on FIG. 1
with the X-axis moving downward, pitch angle 25 may vary from zero
degrees to negative ninety degrees. Roll angle 27 is an angle that
varies between the Y-axis illustrated on FIG. 1 and the horizontal
plane. Roll angle 27 may vary between zero degrees and positive
ninety degrees when rotating thermal imaging camera 10 around the
X-axis illustrated on FIG. 1 with the Y-axis moving upward and zero
degrees and negative ninety degrees when rotating the camera around
the X-axis illustrated on FIG. 1 with the Y-axis moving downward.
The accelerometer can therefore supply position data in the form of
orientation data that indicates the orientation of the camera 10
during use.
[0060] In embodiments where the position sensor includes an
accelerometer and a compass, measurements from each may be captured
at substantially the same time or at different times. The magnetic
sensor and accelerometer may be separate components or they may be
formed by a single component such as, e.g., a MEMS
(micro-electro-mechanical-system) package.
[0061] When thermal imaging camera 10 is configured with magnetic
sensor and accelerometer, processor 106 can determine a physical
orientation of the camera in three-dimensional space. Thermal
imaging camera 10 may process magnetic field strength signals
and/or accelerometer signals generated by the compass to determine
an orientation of the thermal imaging camera, e.g., relative to an
absolute reference system (e.g., X, Y, Z coordinate system) fixed
with respect to ground and an orientation of housing 12 of the
camera. Thermal imaging camera 10 may then store the orientation
information in memory and/or display the orientation information on
display 18. The combined magnetic sensor and accelerometer can
therefore supply position data in the form of orientation data that
indicates the physical orientation of the camera 10 in
three-dimensional space during use.
[0062] During use, thermal imaging camera 10 may display on display
18 information representative of the orientation of the camera at
any given physical orientation in three-dimensional space. For
example, thermal imaging camera 10 may display information
representative of heading angle 23, pitch angle 25, and/or roll
angle 27 on display 18. Although thermal imaging camera 10 may
display any suitable orientation information, a user may find
heading information representative of the orientation angle that
varies with respect to the magnetic north pole most useful.
Accordingly, in one example, thermal imaging camera 10 is
configured to display heading information generated via an
electronic compass located within housing 12 on display 18. Example
heading information that may be displayed by thermal imaging camera
10 includes cardinal ordinate information (e.g., N, NE, E, SE, S,
SW, W, NW) corresponding to the direction the camera is pointed,
declination angle information (e.g., in degrees) with respect to
magnetic north corresponding to the direction the camera is
pointed, or the like.
[0063] In certain embodiments, the position sensor 118 may also
include a global positioning system (GPS) receiver. The GPS
receiver receives GPS signals for the purpose of determining the
thermal imager's 10 current location on Earth. In particular, the
GPS receiver can provide latitude and longitude information of the
location of the thermal imager. In certain embodiments, the GPS
receiver may also provide the altitude of the thermal imager 10.
Since thermal imager 10 is often used indoors, the GPS receiver may
include assisted GPS or other technology to permit the GPS to
operate reliably indoors. For instance, the GPS receiver may
operate in conjunction with WiFi access points, cellular phone
masts, or other terrestrial radios distributed throughout a
building and/or nearby a building that would assist the GPS with
triangulating its location when indoors. The position sensor 118
may include and employ additional sensor and processing
technologies to help increase location accuracy when the camera 10
is used indoors. For instance, the position sensor, in some
embodiments, may include a pressure sensor to increase the accuracy
of the altitude of the camera 10. Position sensor 118 may include a
gyroscope that works with the accelerometer to provide improved
inertial navigation. Position sensor 118 could also include a step
counter with a variable stride length setting to increase the
accuracy of the inertial navigation. Such sensors could also be
employed to utilize dead reckoning techniques that help determine
the new position based on knowledge gathered of a previous known
location (e.g., via the GPS when outdoors) utilizing current
distance and heading information detected by other sensors (e.g.,
accelerometer, compass) within the position sensor 118.
[0064] In addition, memory 110 may be programmed with a map
database. The map database may include both outdoor and indoor
(e.g., internal building) maps to help direct the user back to the
same location within a building. During use, the processor 106 can
receive an electronic signal from GPS receiver of position sensor
118 representative of the location on Earth (e.g., latitude,
longitude, altitude, etc.) of the thermal imager 10 measured by the
GPS receiver at any time. The processor 106 may process such
signals to determine the location of the thermal imager 10 relative
to a location on the map database stored in memory 110. Thermal
imaging camera 10 may then store the GPS location in memory and/or
display the GPS location information on display, either with or
without the associated location on the map.
[0065] Based on the position data that includes location, heading,
and orientation data (alone or in combination) provided by position
sensor 118, processor 106 may also provide instructions to the user
how to return to a desired location, such as a new location or the
location where an image was previously captured by the same thermal
imager 10 or by another imager. Turn-by-turn instructions may be
provided to the user via display or via some other feedback
mechanism (audio) to guide the user to the desired location. The
instructions may be provided in conjunction with an internal
building map or other reference map. Once at the desired location,
the processor 106 may further provide instructions to the user
regarding the desired heading (via compass data) and the desired
orientation (via accelerometer data).
[0066] During operation of thermal imaging camera 10, processor 106
controls infrared camera module 100 and visible light camera module
102 with the aid of instructions associated with program
information that is stored in memory 110 to generate a visible
light image and an infrared image of a target scene. Processor 106
further controls display 104 to display the visible light image
and/or the infrared image generated by thermal imaging camera 10.
Memory 110 can further store infrared and visible light images
along with data regarding the camera position and settings used to
obtain the images.
[0067] The program information can further be used by the processor
106 to control the operations necessary for retaking the infrared
image or fused visible light and infrared image in the same
position as an earlier image. For example, the processor 106 can
process the position data and setting data associated with a stored
image. It can further process data relating to the thermal imaging
camera's current position, determine what position changes are
needed to align the current position with the previous position,
and direct a user to reposition the camera 10 until the original
camera position is achieved or until the position is adequately
close to the original position. In some embodiments, the processor
106 may further direct the user to apply the previous settings or
it may automatically set the camera 10 to the previous settings.
Finally, when the processor 106 determines that the position of the
thermal imaging camera 10 is sufficiently close to the original
position, it can direct the thermal imaging camera 10 to
automatically capture an infrared or fused infrared and visible
light image or can direct the user to capture the image.
[0068] In some embodiments, the position data indicate a location
of a thermal imaging camera 10 when an image is captured includes
the distance-to-target, the aiming point, and the pitch, roll and
yaw of the thermal imaging camera 10. This data is generated at the
time an image is captured and is stored with or associated with the
image, and can also be detected during camera 10 positioning at a
later time. The distance-to-target may be determined as described
above using the laser or the lens position. The aiming point is the
specific point in the image at which the focal distance was
determined. The aiming point may be displayed on the display 18 of
the thermal imaging camera 10 or on a separate display dedicated to
displaying the aiming point. The aiming point could be indicated in
one or more ways, including via visual indications, such as textual
descriptions, arrows, sights (simple sight, optical sight,
telescopic sight, reflector sight, globe sight, etc.), via audible
indications (spoken directions), and/or via vibrational
indications.
[0069] The user may be directed to reposition the camera 10 while
maintaining the current aiming point at the same point as the
original aiming point. The position data regarding pitch and roll
may be obtained from accelerometers within the thermal imaging
camera 10 and the position data regarding yaw can be obtained from
a compass within the thermal imaging camera 10. By reproducing the
distance-to-target, aiming point, pitch, roll, and yaw used when
capturing an earlier image, the earlier position of the thermal
imaging camera 10 can be replicated.
[0070] FIG. 6 presents a flow chart of a process for retaking an
infrared or fused visible light and infrared image according to
some embodiments of the invention. At some previous time, a first
image was captured at a first position by a thermal imaging camera
10. This first image may be an infrared image or a fused infrared
and visible light image, for example. The first image may be stored
in the memory 110 of the thermal imaging camera 10 or may be
transferred to a separate digital storage medium. First image
position data, which provides an indication of the first position
and was captured along with the first image, is stored in
association with the first image. At step 310, the first image and
the first image position data are retrieved by a thermal imaging
camera 10. This thermal imaging camera 10 may be the same thermal
imaging camera 10 as used to capture the first image or may be a
separate thermal imaging camera 10 which includes the same position
sensor 118 as the other thermal imaging camera 10.
[0071] At step 320 the thermal imaging camera 10 obtains current
position data which provides an indication of the current position
of the thermal imaging camera 10. At step 330, the thermal imaging
camera processes the current position data and the first image
position data to determine the difference between the first
position and the current position. The first position data and the
current position data may be data provided by accelerometers,
compass and/or GPS components, for example, depending on the type
of position sensor 118 present within the thermal imaging camera
10.
[0072] At step 340, the thermal imaging camera 10 determines
whether or not the first position and the current position are
sufficiently close to retake the image. If they are not
sufficiently close and repositioning is required, the thermal
imaging camera 10 directs the user to reposition the thermal
imaging camera toward the first position at step 350. For example,
the thermal imaging camera 10 may signal the user by sending
information to the display 18 (which may include a separate,
dedicated aiming point display), such that the display indicates
the type and direction of repositioning that is required. New
current position data is then obtained at step 320 and the position
data is again processed at step 330. This cycle of steps may occur
repeatedly and continuously as the user repositions the thermal
imaging camera 10 toward the first position in response to signals
from the thermal imaging camera 10. In certain embodiments, the
user is directed in real time how to reposition the thermal imaging
camera until the thermal imaging camera is at or is sufficiently
close to the first position to retake the image of the object or
scene.
[0073] Once the thermal imaging camera 10 determines that the first
position and the current position are sufficiently close, the
thermal imaging camera 10 captures a second image at a second
position at step 360. The second image may be captured
automatically by the thermal imaging camera 10, or the thermal
imaging camera 10 may signal the user to manually capture the
second image for this step.
[0074] In some embodiments, setting data is also stored in
association with the first image. The setting data provides
information regarding the first settings of the camera, which were
the settings at the time the first image was captured. This data
may be retrieved by the thermal imaging camera 10 along with the
first image and first image position data. The setting data may be
processed by the thermal imaging camera 10 and one or more or all
the stored first settings may be automatically applied to the
thermal imaging camera 10 and/or the thermal imaging camera 10 may
signal the user to manually apply one or more or all of the stored
first settings (such as by indicating on the display the settings
to be applied by the user), prior to capturing the second
image.
[0075] In some embodiments, the second image is the same type of
image as the first image. For example, the first and second images
may both be infrared images or both be fused images. In other
embodiments, the first image and the second image may be different
types of images. For example, the first image may be a visible
light image (which may be associated with an infrared or fused
image with which it may have been captured simultaneously or at
approximately the same time) and the second image may be an
infrared or fused image.
[0076] The determination of whether the current position is
sufficiently close the first position can be made by the processor
106 using the program information. For example, a particular amount
of tolerance for variation from the first position may be pre-set
into the program information of the thermal imaging camera 10.
Alternatively, various levels of tolerance may be provided for in
the program information, and the user may select which level of
tolerance should be applied for retaking a particular image. In
some embodiments, when an image is captured at a position that is
sufficiently close (within the allowed tolerance) and a second
image is captured, the processor may shift (recenter) the captured
second image to align more exactly with the original image. This
shift may occur automatically or at the direction of the user.
[0077] By having first and second infrared images, captured at
different points in time but from generally the same position, a
comparison may be made to determine how the infrared images have
changed. In this way, the first infrared image or fused infrared
and visible light image may be compared to the second infrared
image or fused infrared and visible light image, so that changes in
the infrared aspect of the image, representing changes in heat
patterns, may be more easily identified. The comparison may be made
from a side-by-side manual comparison. The images could also be
superimposed to more easily identify thermal shifts. Or, the
processor 106 or other non-camera software could be employed to
perform a thermal analysis of the two infrared images to identify
thermal differences. A thermal shift may indicate a potential
malfunction that can be remedied before it becomes a larger
problem.
[0078] Example thermal image cameras and related techniques have
been described. The techniques described in this disclosure may
also be embodied or encoded in a computer-readable medium, such as
a non-transitory computer-readable storage medium containing
instructions. Instructions embedded or encoded in a
computer-readable storage medium may cause a programmable
processor, or other processor, to perform the method, e.g., when
the instructions are executed. Computer readable storage media may
include random access memory (RAM), read only memory (ROM), a hard
disk, optical media, or other computer readable media.
[0079] Various examples have been described. These and other
examples are within the scope of the following claims.
* * * * *